Tachometer



Nov. 23 *1926. 1,608,130

' K. G. MAGNI' TACHO'METER 'Filed Feb. 2l, 1924 Patented Nov. 23, 1926.

UNITED STATESl PATENT orrics.

.KARL GUNNAB. MAGnI, er LinKo'rtNe, swnDEN.

TACHOMETER.

ApplicationV filed February 21, 1924, Serial No. 694,444, and in Sweden April G, 192B.

rlhe device herein described is intended to make known by acoustic signals whether a machine, )for instance a separator, is driven with the right speed. The device is most suitable for a low number of revolutions 50-100 rev/min.

The invention is clearly illustrated in the accompanying drawings, in which Fig. l is a rear elevational view of thel panying drawing, the tachometer consists principally of a turnable member a on which are arranged a bell b or such like, a pendulum, consisting of a swingably hung tongue or hammer c and a carrier d, which forces the tongue to participate in the rotation of the member a but which in a certain posi tion permits the same to fall against the bell. The tongue thus makes an oscillation or a. part thereoiQ as a result of the action of the torce of gravitation. As long as a certain angular velocity is not exceeded the tongue c will hit the bell once during each revolution, the bell during the swinging movement of the tongue moving for instance to a substantially vertical position. If said angular velocity is exceeded the swinging velocity of the tongue is increased, it is true, but not in proportion to the number of revolutions. The tongue for that reason turns back to the carrier Z before it has reached the bell.

rI`he device thus vtullillsr its purpose in that it rings the sounding member when the speed of the machine exceeds a certain value and ceases to ring when the speed falls below a certain value.

By moving the bell Z9 or the carrier Z in a suitable way, for instance along an arc, concentric to the pivot of the tongue, and xing it in the new position it is possible toadjust the device for the desired number.

of revolutions. The same result may be obtained by lengthening or shortening the pendulum or tongue 0.

rlhe sheet member a is to be fastened by being ammed firmly under the nut of the crank pin of a hand driven separator7 (not land threaded on to the shaft.

shown), and the projections z' are to be bent around the crank. rlhe bell Z) is fastened to the shaft the peg ot which is journaled in the sheet member a and is kept into contact with it by means ot a spring g, which catches into two (or one or more) grooves in the peg. On the shaft j is swingably hung a pendulum or hammer c, formed as a bow, both ends ot' which are provided with holes The bell l) is provided with a pin 7L, against which the hammer may beat. The pin may be eX- changed for a shoulder or a projection eX- tending from the rim ot the bell, which projection is turned inward, as shown in Fig. 3. Out from the sheet member a is Pressed a spring d, which acts as a carrier for the hammer c. The bell with the pin h may be turned solely together with the spring r, whereby the point ot' said spring slides over depressions'or grooves in the sheet member (see Fig. 2) and is held in one of them, when the turning is ended. rlhe pin L may thus be fixed in different positions in relation to the parts a and b, that is, the tachometer may be adjusted for the desired number of revolutions, as stated before.

In the embodiment shown the carrier may be provided with a cushion e or such like of elastic. or soft material on the points where it is contacted by thehammer,

Having now described my invention, what I claim as new and desire to secure by Letters Patent is l. A tachometer tor rotatable machine members comprising a rotatable member adapted to partakev in the rotation of the machine member, a carrier on said rotatable member, a sounding member secured to the rotatable member, the bell being turnable and likable in different positions in relation to the rotatable member and the carrier, a swingable pendulum with the swinging center situated at the central part of the bell, a. shoulder mounted on the bell to stop the pendulum and transmit the strokes ot the pendulum to the bell, the pendulum alternately resting against the carrier and alternately performing a falling movement relative to the carrier approximately in its own plane ot rotation in order to hit the shoulder ot the bell rotating with the carrier.

2. A tachometer in accordance with claim l, wherein the sounding member is in the form ot a bell, a tubular shaft on the rotatable member, a grooved peg carried by the bell and tnrnably mounted in the shaft, and a resilient member engageable With the grooves in the peg for retaining` the bell in position.

3. A tacliometer in accordance With claim l7 adapted to be mounted on a hand crank, wherein the rotatable member is in the form of a frame provided with a hole for engagement about the hand crank of the machine, and bendable projections extending from the frame adapted to be bent around the crank for attaching it lirmly thereto.

In Witness whereof, I have hereunto signed my name.

KARL GUNNAR MAGNI. 

